The invention relates to a water jet device.
Such water jet devices are used particularly in the field of human medicine.
Such a water jet device is described in EP 0 551 920 B1. This water jet device substantially comprises a pressure generator, a cylinder piston unit and a severing device in the form of a specific operating hand piece. In the cylinder space of the piston cylinder unit, a cartridge being filled with a sterile severing liquid is inserted in a form-fit manner. This cartridge, on the one hand, contacts the piston of the piston cylinder unit, and is connected to the operating hand piece via a pressure line, on the other hand. During operation, the pressure fluid of the pressure generator loads the piston cylinder unit and so the cartridge, and as a result of which the severing liquid is discharged from the cartridge toward the operating hand piece. There, the severing liquid comes out in the form of a fine jet of liquid. By separation of the severing liquid circuit from the pressure liquid circuit and by means of a special design of all instrument components of the severing liquid circuit a continuous chain of sterility is ensured.
However, due to the limited filling volume of the cartridge it turned out that such a water jet device is not suited for these cases of application which require a greater quantity of severing liquid. This disadvantage relates to all applications of plastic surgery, in particular liposuction. Another disadvantage is in that for specific cases of application, the uniformly emerging jet of liquid has to be pulsed with an auxiliary unit. This expense is relatively high.
From U.S. Pat. No. 6,216,573 B1 a water jet device has become known now which does not have these disadvantages. This water jet device comprises a higher situated storage container for the severing liquid, a piston pump and an operating hand piece. The higher situated storage container is connected to the piston pump via a descending line and a pressure line leads from the piston pump to the operating hand piece. For this purpose, the piston pump comprises a pump casing having the piston cylinder unit and an eccentric drive propelling the piston of said piston cylinder unit wherein a membraneous liquid bladder is inserted into the cylinder space of the piston cylinder unit, and the residual cylinder space is charged with a pressure liquid. The membraneous liquid bladder, on the one hand, is connected to the storage container via the descending line and to the operating hand piece via an opening check valve and via the pressure line, on the other hand. The membraneous liquid bladder is generally and alternately pressurized with overpressure or subpressure by the motion of the piston such that the severing liquid in the storage container is drawn in a pulsating manner and is subsequently fed in a pulsating manner toward the operating hand piece. However, this water jet device has disadvantages. Thus, the piston cylinder unit does not generate any defined and sharp severing jet due to the severing jet being mainly determined by the volume change of the liquid bladder, and this volume change is not reproducible because the liquid bladder is merely fixed by two liquid columns. The piston cylinder unit is not efficient enough either. Primarily, it has to do with the fact that the direction of the liquid stream arriving into the liquid bladder and the direction of the pressure liquid stream emerging from the liquid bladder are acting in opposite direction. This results in turning back of the liquid flow within the liquid bladder and so in turbulences and drop in pressure.
It is also disadvantageous that there are two separate liquid circuits again which are to be separated from each other with high expense due to the requirement of sterility. However, an important disadvantage is in that the piston cylinder unit and the eccentric drive are accommodated in a common pump casing which because of that becomes largely and heavily constructing and may only be used fixedly. This raises the price of manufacturing and restricts the functional range strongly since the volume of the liquid bladder is merely designed for a selected range of application. Adaptation of the piston cylinder unit to different cases of application having a greater need of severing liquid is not possible due to the compactness of the pump casing, and the use of a larger liquid bladder in the existing pump casing has to be ruled out because the liquid bladder and the piston cylinder unit have to be well-matched to each other.
As a result, the invention is based on the development of a water jet device according to type for severing a biological structure which is built up in accordance with the modular design principle, and which can be adapted to different cases of application by means of substitution of individual instruments.
The novel water jet device eliminates the abovementioned disadvantages of the prior art.